X-ray diffractometer having means for cooling crystal mounted thereon

ABSTRACT

An X-ray diffractometer having cooling means, mounted on the full-circle portion of the goniometer assembly, for directing the flow of a cooling fluid about the mounted crystal. The cooling means is of such configuration that the longitudinal axis of the output member is always aligned in a fixed relationship, generally along, the phi -axis on which the crystal is mounted. Such alignment enables the mounted crystal to be uniformly bathed in the flow of the cooling fluid whereby differential cooling of different portions of the mounted crystal is avoided. Means, mounted on the full-circle, deflects the stream of cooling fluid and thus protects the goniometer head from frost or condensation, without need to modify the structure of the goniometer head per se.

United States Patent 91 Hall [451 Jan. 14, 1975 X-RAY DIFFRACTOMETER HAVING MEANS FOR COOLING CRYSTAL MOUNTED THEREON [52] US. Cl. 250/272, 250/277 [51] Int. Cl. G0ln 23/20 [58] Field of Search 250/272, 273, 277, 278,

[56] References Cited UNITED STATES PATENTS 6/1965 Patser 250/439 OTHER PUBLICATIONS X-Ray Specimen Temperature Control With Gas Streams by R. A. Young from Journal of Scientific Instruments, Vol. 43, No. 7, July, 1966, pp. 449453.

Primary Examiner-James W. Lawrence Assistant ExaminerC. E. Church Attorney, Agent, or FirmJoseph l. Hirsch; William B. Walker [57] ABSTRACT An X-ray diffractometer having cooling means, mounted on the full-circle portion of the goniometer assembly, for directing the flow of a cooling fluid about the mounted crystal. The cooling means is of such configuration that the longitudinal axis of the output member is always aligned in a fixed relationship, generally along, the dz-axis on which the crystal is mounted. Such alignment enables the mounted crystal to be uniformly bathed in the flow of the cooling fluid whereby differential cooling of different portions of the mounted crystal is avoided. Means, mounted on the full-circle, deflects the stream of cooling fluid and thus protects the goniometer head from frost or condensation, without need to modify the structure of the goniometer head per se.

7 Claims, 3 Drawing Figures X-RAY DIFFRACTOMETER HAVING MEANS FOR COOLING CRYSTAL MOUNTED THEREON FIELD OF THE INVENTION This invention relates to X-ray diffractometers having means for coolinng the crystal mounted thereon for analysis to temperatures below room temperature.

BACKGROUND OF THE INVENTION This application is related to the crystal cooling means described in copending application Ser. No. 282,151, filed Aug. 21, 1972. In that application there is described an X-ray diffractometer including a fullcircle goniometer assembly having a goniometer head for holding and supporting a crystal to be analyzed; an X-ray source for directing a beam of X-ray radiation at the mounted crystal; detector means positioned to receive the diffracted X-ray beam for measuring the intensity thereof; and means; mounted on the full-circle portion of the goniometer assembly, for directing the flow of a cooling fluid about the crystal along the axis of the fiber or filament on which the crystal is mounted. The cooling means includes a stationary input member secured to the movable outer ring of the full-circle portion of the goniometer assembly and a output member secured to the movable inner ring of the full-circle portion of the goniometer assembly. By use of this configuration, fluid flow from the output port of the output member is at all times in a fixed relationship with the (ii-axis whereby, during cooling, the mounted crystal is uniformly bathed in the flow of the cooling fluid thereby avoiding differential cooling of different portions of the mounted crystal. Unfortunately, after the cooling fluid passes the mounted crystal it impinges upon the goniometer head supporting the crystal and causes undesirable frosting, etc.

Deflector means, to protect the goniometer head and to create better cooling fluid flow patterns, are known. For example, see Renaud and Fourme Accta Cryst. 22, 695 (1967). Such deflector means, however, require modification of the goniometer head by mounting of the deflector thereon and by adding a heating element at the base thereof. Since modification of each goniometer head is not considered practical, it would be desirable to have a device which achieves the same results, yet does not require undue goniometer assembly modification.

OBJECT OF THE INVENTION It is, therefore, the primary object of this invention to provide a novel X-ray diffractometer including means associated therewith for cooling a crystal mounted thereon for analysis and means, mounted on the fullcircle on the diffractometer, for deflecting the flow of the cooling fluid about the goniometer head.

These and still further objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed disclosure.

BRIEF SUMMARY OF THE INVENTION These and still further objects, features, and advantages of the present invention are achieved, in accordance therewith, by providing an X-ray diffractometer including a full-circle goniometer assembly having a goniometer head for holding and supporting a crystal to be analyzed; an X-ray source for directing a beam of X-ray radiation at the mounted crystal; detector means positioned to receive the diffracted X-ray beam for measuring the intensity thereof; means, mounted on the full-circle portion of the goniometer assembly, for directing the flow of a cooling fluid about the crystal along the axis of the fiber or filament on which the crystal is mounted; and means, also mounted on the fullcircle portion of the goniometer assembly, for deflecting the flow of the cooling fluid after it has passed the mounted crystal. The deflector means and the goniometer head assembly are both supported by the movable, inner ring of the full-circle and, accordingly, will remain in a fixed position, one relative to the other, during all movements of the X-ray diffractometer.

The deflector per se comprises a non-planar plate highest at about the center portion thereof and sloping downwardly in an uniform manner toward the outer perimeter thereof (that is, the plate is essentially conically shaped with a height to diameter ratio of less than one). A rod like support is attached to the upper surface of the deflector plate to enable the deflector plate to be mounted on mounting means attached to the inner movable ring of the full-circle. A slot is provided in the deflector plate to permit the crystal supporting means to extend from beneath the deflector plate to above the deflector plate, whereby access to the mounted crystal may readily be had during conditions of use. In addition, strip heater means are provided on the underneath surface of the deflector plate to maintain the deflector plate at an appropriate temperature so undesirable frosting thereof does not occur during use.

As indicated above, this application describes deflector means adapted for use with the X-ray diffractometer and cooling means more particularly described in copending application Ser. No. 282,151. That application, and the disclosure thereof, are incorporated herein by reference. Reference should be had thereto for a more complete description of certain components of this system.

The cooling means associated with the X-ray diffractometer is connected, via a supply conduit, to a source of the cooling fluid. For example, the cooling means can be connected to a source of dry nitrogen gas, or, alternatively, to a source of liquid nitrogen which is converted to the gaseous state before actual use. Whatever source is selected, it is essential, however, that the cooling fluid be dry as it flows about the mounted crystal, otherwise frosting will occur on the crystal which, quite obviously, is highly undesirable. When the cooling means is connected to a, source of dry nitrogen gas, it is presently preferred to pass such dry gas through a heat exchanger immersed in a bath of liquid nitrogen, whereby the nitrogen gas, without coming in contact with other fluids, such as air, is cooled to the temperature of liquid nitrogen. The liquid nitrogen surrounding the heat exchanger can be connected to a source of liquid nitrogen, and sensors can be provided to insure that the heat exchanger is totally immersed in the liquid nitrogen at all times. The temperatures of the cooling fluid as it exits from the outlet port of the cooling means can be regulated by providing a heating coil in the supply conduit between the heat exchanger and the above-described cooling means. By regulating the heat input to the heating coil, the temperature of the cooling fluid can be regulated, for example, between liquid nitrogen temperature and room temperature.

As the cooling fluid exits from the outlet port of the cooling means, it will, of course, come in contact with the humidified ambient atmosphere. There is the possibility that turbulent mixture of the cooling fluid and the humidified air will cause frosting to occur on the mounted crystal as well as on the outlet for the cold stream. Preferably, to avoid such undesirable frosting, an attachment is provided on the outlet end of the cooling means which can be connected, for example, to a source of dry nitrogen gas or dry air. The flow rate through this nozzle attachment is selected so that an annular sheath of dry gas surrounds the cooling fluid as it flows from the outlet port of the cooling means to and around the mounted crystal. In this manner, the moisture in the ambient atmosphere is excluded from the zone about the outlet port of the cooling means and the mounted crystal, whereby undesirable frosting does not occur. Optionally, this result can be achieved by placing the X-ray diffractometer of the present invention in an environmental chamber which is continually flushed with a dry gas, or by electrically heating the outer skin of the flowing cooling fluid stream.

After the cooling fluid passes the mounted crystal, it impinges upon the deflector plate and is directed outwardly away from the zone adjacent the mounted crystal. This is done in a reasonably effective manner such that turbulence adjacent the mounted crystal is avoided. In addition, the goniometer head is protected from undesirable frosting since the substantial or main portion of the stream of cooling fluid is deflected away from the goniometer head assembly.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and still further features and advantages of the present invention will become more apparent from the following detailed description, together with the accompanying drawings wherein:

FIG. 1 is an elevational view of an X-ray diffractome ter showing the mounting of the deflection means in the position where the crystal-supporting fiber is vertically oriented;

FIG. 2 is an elevational view (partially in Section) of the deflecting means of this invention; and

FIG. 3 is a bottom view of the deflection means of FIG. 2.

Referring to FIG ll, there is shown an X-ray diffractometer having a base 12 on which there is mounted a goniometer assembly 14 and, in appropriate positions, and X-ray source (not shown) and a detector (not shown). Goniometer assemblly 14 includes a base 16 on which there is mounted for rotation a full-circle 18 having outer ring 20 and movable inner ring 22. Mounted on movable inner ring 22 is a goniometer head 24 upon which a crystal to be analyzed can be mounted. Inner ring 22 is rotated by drive means, schematically shown at 26, and full-circle 18 can be rotated by rotating means, schematically shown at 29. As is well known in this art, goniometer head 24 can be rotated through 360, inner ring 22 can be rotated through 360, and the full circle 18 and the detector can also be rotated, to thereby enable the beam of X- radiation to be directed at any point or plane on the surface of the crystal being analyzed. Goniometer assembly l4, and its associated drive mechanisms, the X-ray source and the detector are of conventional configuration well known to those skilled in this art and, accordingly, are only shown in schematic form.

Mounted on outer ring 20 of full-circle 18 by means of bracket 30 is the stationary input member 32 of cooling means 34. Input member 32 has an enlarged terminal end 36 adapted for connection to supply conduit 38. The other end of input member 32 is connected to intermediate two-bar linkage, as shown in aforementioned application Ser. No. 282,l5 I, having a first arm which is connected, in turn, to second arm. The terminal end of the second arm is connected to output member 40 which by means of another bracket 42 is secured to movable inner ring 22.

As shown in FIG. 1, the longitudinal axis of output member 40 is such that it is always aligned in a fixed relationship with the mounted crystal, i.e., generally along the -axis on which the crystal being analyzed is mounted. As the inner ring 22 of goniometer assembly 14 is rotated the longitudinal axis of outptut member 40 remains in the fixed relationship with the -axis because of the structural configuration of cooling means 34. The mounted crystal, accordingly, will be uniformly bathed in the flow of the cooling fluid and, thus, uniformly cooled. This is achieved, however, without need for complex cooling arrangements or enclosures which, as indicated above, undesirably restrict access to the mounted crystal.

A nozzle attachment 44 is provided about the terminal end of output member 40. Such nozzle attachment is preferably of the configuration as shown in FIG. 9 of application Ser. No. 282,151, or as shown in FIG. 5 thereof. Such nozzle attachment can be connected to a source of dry gas via its own supply conduit. By properly adjusting the respective flow rates of the cooling fluid and the dry gas, there is provided an annular sheath of dry gas surrounding the cylindrical flow of cooling fluid. Thus, as the cooling fluid and the dry gas pass around the mounted crystal, there will be little or no contact of the cooling fluid with the humidified ambient atmosphere whereby undersirable frosting on the surface of the mounted surface of the mounted crystal will not occur. To the extent that the flow rate of the cooling fluid itself can be adjusted to prevent frosting or condensation on the surface of the mounted crystal, without need for the nozzle attachment and the annular sheath of dry gas, or a dry gas flushed environmental chamber is provided, such nozzle attachment, etc. can be omitted; however, as a purely precautional measure, it is presently preferred to provide such means and thereby positively ensure that undesirable frosting will not occur.

Cooling means 34 may alternatively have the configuration as shown in FIG. 6 of application Ser. No. 282,151.

Referring to FIGS. 2 and 3, there is shown deflector means 46 having hollow support rod 48 by which the deflector plate is attached to support 49 mounted on bracket 42. At the base of rod 48 adjacent goniometer head 24 there is conically-shaped deflector plate 50 which, as can be seen in FIG. 3, has a notch 52 therein to permit easy access to mounted crystal 54 supported by fiber 56 and upper portion 58 of the goniometer head. Notch 52 is of such configuration that upper portion 58 supporting a crystal 54 passes through innermost end 60 of notch 52. As shown, the notch extends from the outer perimeter of deflector plate 50 to the central portion thereof, although undoubtedly other configurations are feasible and will allow both easy mounting of the deflector means and ready access to the mounted crystal and the supporting goniometer head.

n the lower surface of the deflector plate 50 there is a heating element 62 connecting to thermostat 64, from which wire 56 passes through the hollow portion 68 of support rod 48 to control means (not shown). The thermostat is intended to protect heating element 62 in the event of interruption of the flow of the cooling fluid against the deflector plate. As the temperature of the upper surface increases to, or above, a predetermined upper limit, the thermostat cuts off power to the heating element.

Rod 48 is secured to bracket 49 by means of clamp 70 having tightening screws 72. Rod 48 is slidable, along the longitudinal axis thereof, through bore 74 in clamp 70, thus permitting deflector plate 50 to be positioned at the desired plane between mounted crystal 54 and goniometer head 24. Additionally, since rod 48 is freely rotatable within bore 74, the deflector plate can be rotated along the horizontal plane shown in FIG. 1, thereby permitting notch 2 to be positioned as desired (e.g., for better access to goniometer head 24, mounted crystal 54, fiber 56 or support 58, etc.).

Thus, there is described means to deflect the major portion of the stream of cooling fluid from direct contact with the goniometer head, thereby preventing undersirable frosting and jamming thereof during data collection. This is achieved without need for modification of existing, or factory assembled, goniometer heads, and, in addition, enables easy access to the mounted crystal and the supporting goniometer head.

While the present invention has been described with reference to specific embodiments thereof, it should be understood by those skilled in this art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material or composition of matter, process, process step or steps, or then-present objective to the spirit of this invention without departing from its essential teachings.

What is claimed is:

1. An X-ray diffractometer comprising a goniometer assembly includinng a full-circle having an outer ring and a movable inner ring, and a rotatable goniometer head mounted on said movable inner ring for holding and supporting a crystal to be analyzed; an X-ray source for directing a beam of X-radiation at the mounted crystal; detector means for receiving and measuring the intensity of the X-ray beam diffracted by the mounted crystal; means mounted on said full-circle for directing the flow of a cooling fluid about the mounted crystal, said means comprising an input member secured to said outer ring of said full-circle and an output member secured to said movable inner ring of said full-circle, said output member having a component part thereof directed so that fluid flow therefrom is at all times in a fixed relationship with the ib-axis of said X-ray diffractometer on which the crystal is mounted whereby, during cooling, the mounted crystal is uniformly bathed in the flow of the cooling fluid; and means, mounted on said movable inner ring of said fullcircle free of attachment to said goniometer head, for deflecting the flow of the cooling fluid after said cooling fluid passes the mounted crystal whereby said goniometer head remains frostfree during data collection.

2. The X-ray diffractometer of claim 1 wherein said deflector means comprises a substantially conically shaped deflector plate having an opening at the apex thereof, and means for connecting said deflector plate to said movable inner ring; said connecting means being of such length that said deflector plate is positioned on the opposite side of the mounted crystal from that portion of said connecting means attached to said movable inner ring; said opening adapted to have the crystal supporting means associated with said goniometer head and the mounted crystal supported thereby extending therethrough from beneath said deflector plate toward said component part of said output member.

3. The X-ray diffractometer of claim 2 wherein said opening comprisees a substantially rectangular notch extending from said apex to the outer periphery of said deflector plate.

4. The X-ray diffractometer of claim 2 wherein said deflector plate has associated therewith heater means for maintaining the temperature of said deflector plate above a predetermined temperature during use, whereby undesirable frosting of said plate does not occur.

5. The X-ray diffractometer of claim 4 wherein said heater means comprises a heating element affixed to that surface of said deflector plate closest to said goniometer head, and means connected to said heating element for cutting power to said heating element when the temperature of said deflector plate rises above a predetermined temperature during use.

6. Means for directing the flow of a cooling fluid about a mounted crystal in an X-ray diffractometer, the X-ray diffractometer including a goniometer assembly including a full-circle having an outer ring and a movable inner ring and a rotatable goniometer head mounted on the movable inner ring for holding and supportitng a crystal to be analyzed; said flow directing means comprising an input member adapted to be secured to the outer ring of the full-circle and an output member adapted to be secured to the movable inner ring of the full said output member having a component part thereof directed so that flow of the cooling fluid therefrom is at all times in a fixed relationship with the draxis of the X-ray diffractometer on which the crystal is mounted, whereby, during cooling, the mounted crystal is uniformly bathed in the flow of the cooling fluid; and means, adapted to be secured to the movable inner ring of the full-circle without attachment to the rotatable goniometer head, for deflecting the flow of cooling fluid after the cooling fluid passes the mounted crystal whereby the goniometer head remains frost-free during data collection.

7. The means of claim 6 wherein said deflector means comprises a substantially conically shaped deflector plate having an opening at the apex thereof, and means for connecting said deflector plate to said movable inner ring; said connecting means being of such length that said deflector plate is positioned on the opposite side of the mounted crystal from that portion of said connecting means attached to said movable inner ring; said opening adapted to have the crystal supporting means associated with said goniometer head and the mounted crystal supported thereby extend therethrough from beneath said deflector plate toward said component part of said output member; said deflector plate having associated therewith heater means for maintaining the temperature of said deflector plate above a predetermined temperature during use, said heater, means comprising a heating element affixed to that surface of said deflector plate closest to the goniometer head, and means connected to said heating element for cutting power to said heating element when the temperature of said deflector plate rises above a predetermined temperature during use. 

1. An X-ray diffractometer comprising a goniometer assembly includinng a full-circle having an outer ring and a movable inner ring, and a rotatable goniometer head mounted on said movable inner ring for holding and supporting a crystal to be analyzed; an X-ray source for directing a beam of X-radiation at the mounted crystal; detector means for receiving and measuring the intensity of the X-ray beam diffracted by the mounted crystal; means mounted on said full-circle for directing the flow of a cooling fluid about the mounted crystal, said means comprising an input member secured to said outer ring of said full-circle and an output member secured to said movable inner ring of said full-circle, said output member having a component part thereof directed so that fluid flow therefrom is at all times in a fixed relationship with the phi -axis of said X-ray diffractometer on which the crystal is mounted whereby, during cooling, the mounted crystal is uniformly bathed in the flow of the cooling fluid; and means, mounted on said movable inner ring of said full-circle free of attachment to said goniometer head, for deflecting the flow of the cooling fluid after said cooling fluid passes the mounted crystal whereby said goniometer head remains frostfree during data collection.
 2. The X-ray diffractometer of claim 1 wherein said deflector means comprises a substantially conically shaped deflector plate having an opening at the apex thereof, and means for connecting said deflector plate to said movable inner ring; said connecting means being of such length that said deflector plate is positioned on the opposite side of the mounted crystal from that portion of said connecting means attached to said movable inner ring; said opening adapted to have the crystal supporting means associated with said goniometer head and the mounted crystal supported thereby extending therethrough from beneath said deflector plate toward said component part of said output member.
 3. The X-ray diffractometer of claim 2 wherein said opening comprisees a substantially rectangular notch extending from said apex to the outer periphery of said deflector plate..
 4. The X-ray diffractometer of claim 2 wherein said deflector plate has associated therewith heater means for maintaining the temperature of said deflector plate above a predetermined temperature during use, whereby undesirable frosting of said plate does not occur.
 5. The X-ray diffractometer of claim 4 wherein said heater means comprises a heating element affixed to that surface of said deflector plate closest to said goniometer head, and means connected to said heating element for cutting power to said heating element when the temperature of said deflector plate rises above a predetermined temperature during use.
 6. yMeans for directing the flow of a cooling fluid about a mounted crystal in an X-ray diffractometer, the X-ray diffractometer including a goniometer assembly including a fullcircle having an outer ring and a movable inner ring and a rotatable goniometer head mounted on the movable inner ring for holding and supportitng a crystal to be analyzed; said flow directing means comprising an input member adapted to be secured to the outer ring of the full-circle and an output member adapted to be secured to the movable inner ring of the full said output member having a component part thereof directed so that flow of the cooling fluid therefrom is at all times in a fixed relationship with the phi -axis of the X-ray diffractometer on which the crystal is mounted, whereby, during cooling, the mounted crystal is uniformly bathed in the flow of the cooling fluid; and means, adapted to be secured to the movable inner ring of the full-circle without attachment to the rotatable goniometer head, for deflecting the flow of cooling fluid after the cooling fluid passes the mounted crystal whereby the goniometer head remains frost-free during data collection.
 7. The means of claim 6 wherein said deflector means comprises a substantially conically shaped deflector plate having an opening at the apex thereof, and means for connecting said deflector plate to said movable inner ring; said connecting means being of such length that said deflector plate is positioned on the opposite side of the mounted crystal from that portion of said connecting means attached to said movable inner ring; said opening adapted to have the crystal supporting means associated with said goniometer head and the mounted crystal supported thereby extend therethrough from beneath said deflector plate toward said component part of said output member; said deflector plate having associated therewith heater means for maintaining the temperature of said deflector plate above a predetermined temperature during use, said heater means comprising a heating element affixed to that surface of said deflector plate closest to the goniometer head, and means connected to said heating element for cutting power to said heating element when the temperature of said deflector plate rises above a predetermined temperature during use. 